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Start your free trialTinashe Gwariro
4,691 PointsTask 4 of challenge uncomment comments
I have tried everything i keep getting an error not sure what i am doing wrong
This is the error: Are you sure you used the arguments passed in from the main method in Main.java? args[0] is the firstName and args[1] should be the last name
public class Forum {
private String topic;
// TODO: add a constructor that accepts a topic and sets the private field topic
public Forum(String topic) {
//set mTopic to the topic passed in to the constructor
topic = topic;
}
public String getTopic() {
return topic;
}
public void addPost(ForumPost post) {
System.out.printf("A new post in %s topic from %s %s about %s is available",
topic,
post.getAuthor().getFirstName(),
post.getAuthor().getLastName(),
post.getTitle()
);
}
}
public class User {
// TODO: add private fields for firstName and lastName
private String firstName;
private String lastName;
public User(String firstName, String lastName) {
// TODO: set and add the private fields
firstName = firstName;
lastName = lastName;
}
// TODO: add getters for firstName and lastName
public String getFirstName(){
return firstName;
}
public String getLastName(){
return lastName;
}
}
public class ForumPost {
private User author;
private String title;
private String description;
// TODO: add a constructor that accepts the author, title and description
public ForumPost(User author, String title, String description) {
this.author = author;
this.title = title;
this.description = description;
}
public User getAuthor() {
return author;
}
public String getTitle() {
return title;
}
public String getDescription() {
return description;
}
}
public class Main {
public static void main(String[] args) {
System.out.println("Beginning forum example");
if (args.length < 2) {
System.out.println("Usage: java Main <first name> <last name>");
System.err.println("<first name> and <last name> are required");
System.exit(1);
}
Forum forum = new Forum("Java");
String firstName = args[0];
String lastName = args[1];
User author = new User(firstName, lastName);
ForumPost post = new ForumPost(author, "Programming is awesome", "Cuz it makes us create new stuff");
forum.addPost(post);
}
}
1 Answer
andren
28,558 PointsThe issue is the constructor you have written for the Forum
and User
class.
Take a look at the constructor for ForumPost
(which is correct):
public ForumPost(User author, String title, String description) {
this.author = author;
this.title = title;
this.description = description;
}
And then compare it to the constructor for User
(which is incorrect):
public User(String firstName, String lastName) {
// TODO: set and add the private fields
firstName = firstName;
lastName = lastName;
}
Can you notice any difference between those two constructors beyond the names used?
The difference is the lack of the this
keyword. When you have a field variable and a parameter that has the same name, you have to use the this
keyword to help Java distinguish between the two.
So you have to change the User
constructor like this:
public User(String firstName, String lastName) {
// TODO: set and add the private fields
this.firstName = firstName;
this.lastName = lastName;
}
The same issue applies to the Forum
constructor, which also has to be fixed like this:
public Forum(String topic) {
//set mTopic to the topic passed in to the constructor
this.topic = topic;
}
Once you fix those constructors your code should work fine.
Tinashe Gwariro
4,691 PointsTinashe Gwariro
4,691 PointsAwesome it actually worked thank you